Brazeable terminal body

ABSTRACT

A metal terminal body provided with an external coating of brazing material and a threaded portion for connecting the terminal body to a holding rod which is used for positioning and installing the terminal body, along with one or more conductor wires attached thereto, inside a metal tube. While held by the rod, the terminal body is braced against the tube wall at a selected location by means of a block inserted into the tube by means of another rod and which permits the block to be moved in sliding contact with the holding rod and the tube wall. The tube is externally heated to melt the brazing material on the terminal body to fuse same to the tube wall after which the block is withdrawn and the holding rod is disconnected from the terminal body.

United States Patent Weaver et al.

[54] BRAZEABLE TERMINAL BODY [72] Inventors: Galen K. Weaver; Howard A. Shaffer;

Stephen A. Coughlln, all of Alliance, Ohio [451 July 11,1972

3,409,732 I H1968 Dahlgren et al ..3l7/l0l CM X Primary Examiner-Darrell L. Clay Attorney-J. Maguire [73] Assignee: The Babcock & Wilcox Company, New

York, NY. [57] ABSTRACT [22] Filed: Oct. 12, 1970 A metal terminal body provided with an external coating of brazing material and a threaded portion for connecting the [2]] Appl' 79934 terminal body to a holding rod which is used for positioning R l U s Appucaflon and installing the terminal body, along with one or more conductor wires attached thereto, inside a metal tube. While held [62] 2 1968 by the rod, the terminal body is bracedragainst the tube wall at a selected location by means of a block inserted into the tube by means of another rod and which pennits the block to be ..l74/94 kiliiizfilligolg moved in Sliding Contact with the homing rod and the tube 58] Field i 289/624 wall. The tube is externally heated to melt the brazing material 29/628 01 f on the terminal body to fuse same to the tube wall after which 33'9/275 R 5 the block is withdrawn and the holding rod is disconnected from the terminal body. [56] References Cited UNITED STATES PATENTS 1 Claim, 2 Drawing Figures 3,267,409 8/1966 l-lorwitz.... 174/84 R UX 13 I l5 23y /24 minimum m2 3,676,575

INVENTORS f Galen K. Weaver Howard A. Shaffer BY Srephen A. Coughlin ZTT%NEY BRAZEABLE TERMINAL BODY This is a division of our application Ser. No. 754,889, filed Aug. 23, 1968, now US. Pat. No. 3,535,812 issued Jan. 2, 1971.

The present invention relates in general to the installation of thermocouple and voltage taps within metal tubes, and to a brazeable terminal body useful in making such tap connections to a tube, and more particularly to an apparatus for installing such terminal bodies in tubes of relatively small diameter.

In the prior art, considerable difficulty has been encountered in installing thermocouple and voltage taps at locations deep inside tubes of small diameter, i.e., having inside diameters less than one-half inch. This difficulty is due to the fact that conventional tools cannot be used to make soldered or brazed connections of the taps to the tube wall at points greater than a few diameters distance from the end of the tube. As a result, the connection of such taps to the tube have been effected by means of spring loaded terminals which can be pushed into the tube and bear against its inside wall surface. These spring terminal connections have been found to be unsatisfactory in service because of intermittent or poor contact with the tube wall, and because the spring parts fail in high temperature applications.

The invention avoids these tap connection failure problems through the use of a metal terminal body that can be brazed to the tube wall after the thermocouple or voltage tap lead wires are connected to the terminal body prior to its insertion into the tube.

The terminal body provided with an external coating of brazing material, has a threaded portion for connecting it to the end of a holding rod that is used to insert the terminal body, along with the lead wires attached thereto, into the tube and to position the terminal body at the desired location within the tube.

While held by the rod, the terminal body is forced into contact with the tube inside wall by means of a block inserted into the tube by another rod, and the block is pushed to its desired location by said other rod in sliding contact with the terminal body holding rod and the tube wall.

The tube is externally heated to melt the brazing material on the terminal body so as to fuse same to the tube wall, after which the block and its associated rod are withdrawn and the holding rod is disconnected from the terminal body and also withdrawn.

By reason of the brazing, the terminal body is metallurgically bonded to the tube wall and provides a tap connection having both high thermal conductivity and high electrical conductivity, and which is not subject to deterioration by temperatures below the melting point of the materials employed.

In the drawing:

1 FIG. 1 is a longitudinal view, partly in section, of a tube, and showing a pair of terminal bodies according to a preferred embodiment of the insertion being installed inside the tube with the aid of the positioning apparatus of the invention.

FIG. 2 is a transverse sectional view of the tube shown in FIG. 1 taken along line 2-2.

In FIGS. 1 and 2 there is shown aterminal body 10A that is positioned in contact with the inside wall surface 11 of a metal tube 12, and is ready to be brazed thereto, and also a terminal body 10B which has already been brazed to the tube surface 1 1.

According to a preferred embodiment of the invention, the terminal bodies 10A, 10B are made of metal, as for example steel, and are both of generally cylindrical shape with a reduced diameter section 13 located between their opposite end faces 14 and 15.

On this reduced diameter section 13 is applied a coating 16 of brazing material, as for example, silver solder. As better seen on the unbrazed terminal body 10A, the coating 16 extends around the circumference of the section 13 and preferably covers its entire cylindrical surface with a thickness substantially equal to the difference in radii between the end portions of body 10A and the reduced diameter section 13.

The end face 14 ofbodies 10A, 10B serves to accommodate the connection of one or more electrical conductor wires 17, such as for example, the lead wires from a thermocouple junction or the lead wire of a voltage tap. The connection of such wires 17 to faces 14 is expediently made by welding or brazing. To assure that the wires 17 will not become disconnected from either body 10A, 10B during the brazing thereof to tube surface 11, the brazing material in the coating 16 is chosen so as to have a melting point that is lower than the melting point of the weld or braze .used in connecting wires 17 to faces 14. Accordingly, the connection of wires 17 to faces 14 is made before the terminal bodies 10A, 10B are installed within tube 12 and also before the braze material coating 16 is deposited on thereduced diameter sections 13.

The other end face 15 has an axially extending internally threaded bore 18, as better shown in sectioned body 10A, that serves for releasably connecting the body 10A, 108 to an associated holding rod 19 provided with a similarly threaded end 22.

If desired, the end face 14 of each body 10A, 103 can be drilled to provide. a blind bore (not shown) extending axially toward the threaded bore 18, but not intersecting therewith, for the purpose of receiving the ends of the wires 17 that are to be welded or brazed to the body 10A, 10B.

To install the terminal bodies 10A, 10B inside of tube 12, a rod 19 is screwed into the bore 18 of each body 10A, 10B and with the aid of such rods 19, the bodies 10A, 10B are inserted into tube 12 and individually positioned as desired by manipulating their respective holding rods 19 to hold each body 10A,

' 108 in contact with the inside tube surface 11 at the location of the desired voltage or temperature measuring point.

To facilitate positioning of the terminal bodies 10A, 108 in good heat transfer contact with the tube wall, and to hold them in place until their braze connections thereto have solidified, the invention provides a bracing tool 21. The bracing tool 21 includes a heavy metallic block member 23 connected to the end of a ram rod 24. Block member 23 has a plurality of surfaces 25 positioned for sliding contact engagement with the tube surface 11 so that when inserted into tube 12, the surfaces 25 constrain block member 23 against radial movement relative to the axis of tube 12, while permitting said block member to freely move longitudinally inside the tube 12. In addition, block member 23 as shown has a pair of longitudinal grooves 26 positioned in angularly spaced relation to each other, for example, degrees apart, as measured about the tube [2 axis. These grooves 26 are located and sized so as to encompass a corresponding rod 19 in sliding contact engagement therewith. Accordingly, the grooves 26 maintain the rods 19 and the terminal bodies 10A, 10B to which they are connected in generally parallel relation to the tube 12 axis, and in a predetermined angular spacing thereabout.

With the terminal bodies 10A, 10B positioned by rods 19 and retained in position by bracing tool 21, the tube 12 is then externally heated at the contact regions until the brazing material coating 16 melts and flows by capillary action into the interstices 20 between the bodies 10A, 10B and tube 12 to fuse them to the tube surface 11. As shown in the drawing, the terminal body 103 has already been fused to tube surface 11, and it will be appreciated that after the brazing operation is completed for the body 10A, it will have substantially the same external appearance as terminal body 103.

lt will be appreciated by the artisan that by using rods 19 to position terminal bodies 10A, 10B inside tube 12, it is possible to control the axial distance of each body 10A, 108 from the tube 12 end, as well as the angular position of each body 10A, 108 about the tube 12 axis, with relatively high precision since the required axial insertion distance in each case can be measured and marked off on the rod 19, and the angular position of the body 10A, 108 can be readily gauged from where the rod 19 extends out of the tube 12.

After the braze connections of terminal bodies 10A, 10B have cooled, block member 23 is withdrawn from tube 12 and the rods 19 are unscrewed and removed from tube 12.

l. A terminal body which comprises an all metal body of generally cylindrical configuration and having a reduced diameter section between its ends, at least one electrical conductor brazed to an end of the body, a coating of brazing material borne by the metal body and circumferentially distributed over the exterior surface of the reduced diameter section between the ends of said body, and means disposed in said body to accommodate a releasable connection thereof to a holding tool. 

1. A terminal body which comprises an all metal body of generally cylindrical configuration and having a reduced diameter section between its ends, at least one electrical conductor brazed to an end of the body, a coating of brazing material borne by the metal body and circumferentially distributed over the exterior surface of the reduced diameter section between the ends of said body, and means disposed in said body to accommodate a releasable connection thereof to a holding tool. 